In Visual Studio 2010, you can use the ClickOnce and Windows Installer deployment technologies to deploy Office solutions that target both Microsoft Office 2007 and Microsoft Office 2010. The main advantage of using Windows Installer to deploy your Office solutions is to install application-level add-ins to AllUsers, rather than the current user only.

@Madhur: It requires some manual steps, but it is possible. You will need to install the program into the users' AppData folder rather than Program Files (that part is easy), and use a tool like Orca (part of a Windows SDK) to explicitly indicate that the resulting MSI is "UAC compliant" (VIew->Edit Summary Information -> UAC Compliant). It's been a year or two since I did this, but the instructions on xldennis.wordpress.com/…/uac-compliant (see the section "Windows Vista and UAC Compatibility Applications") correspond to what I remember from my experience. Hope this helps!